#!/usr/bin/env python3
# -*- coding: utf-8 -*-
__author__ ='TT'

import asyncio,logging
import aiomysql

def log(sql,args=()):
    logging.info('SQL: %s' % sql)

async def create_pool(loop,**kw):
    logging.info('create database pool ...')
    global __pool
    __pool=await aiomysql.create_pool(
        host=kw.get('host','localhost'),
        port=kw.get('port',3306),
        user=kw['user'],
        password=kw['password'],
        db=kw['db'],
        charset=kw.get('charset','utf8'),
        autocommit=kw.get('autocommit',True),
        maxsize=kw.get('maxsize',10),
        minsize=kw.get('minsize',1),
        loop=loop

    )

async def select(sql,args,size=None):
    log(sql,args)
    global __pool
    async with __pool.get() as conn:
        async with conn.cursor(aiomysql.DictCursor) as cur:
            await cur.execute(sql.replace('?','%s'),args or ())
            if size:
                rs=await cur.fetchmany(size)
            else:
                rs=await cur.fetchall()
        logging.info('rows returned: %s' % len(rs))
        return rs

async def execute(sql,args,autocommit=True):
    log(sql)
    async with __pool.get() as conn:
        if not autocommit:
            await conn.begin()
        try:
            async with conn.cursor(aiomysql.DictCursor) as cur:
                await cur.execute(sql.replace('?','%s'),args)
                affected=cur.rowcount
            if not autocommit:
                await conn.commit()
        except BaseException as e:
            if not autocommit:
                await conn.rollback()
            raise
        return affected

def create_args_string(num):
    L=[]
    for n in range(num):
        L.append('?')
    return ', '.join(L)


class Field(object):
    def __init__(self,name,column_type,primary_key,default):
        self.name=name
        self.column_type=column_type
        self.primary_key=primary_key
        self.default=default

    def __str__(self):
        return '<%s,%s:%s>' % (self.__class__.__name__,self.column_type,self.name)
    
class StringField(Field):
    def __init__(self,name=None,primary_key=False,default=None,ddl='varchar(100)'):
        super().__init__(name,ddl,primary_key,default)
class BooleanField(Field):
    def __init__(self,name=None,defalut=False):
        super().__init__(name,'boolean',False,defalut)
class IntegerField(Field):
    def __init__(self,name=None,primary_key=False,default=0):
        super().__init__(name,'bigint',primary_key,default)

class FloatField(Field):
    def __init__(self,name=None,primary_key=False,default=0):
        super().__init__(name,'real',primary_key,default)
class TextField(Field):
    def __init__(self,name=None,primary_key=False,default=0):
        super().__init__(name,'text',False,default)
class ModelMetaClass(type):
    def __new__(cls,name,bases,attrs):
        if name=='Model':
            return type.__new__(cls,name,bases,attrs)
        tableName=attrs.get('__table__',None) or name
        logging.info('found model: %s (table: %s)' % (name,tableName))
        mapping=dict()
        fields=[]
        primaryKey=None
        for k,v in attrs.items():
            if isinstance(v,Field):
                logging.info(' found mapping: %s ==> %s ' % (k,v))
                mapping[k]=v
                if v.primary_key:
                    if primaryKey:
                        raise StandardError('Duplicate primary key  for field: %s ' % k)
                    primaryKey=k
                else:
                    fields.append(k)
        if not primaryKey:
            raise StandardError('Primary key not found.')
        for k in mapping.keys():
            attrs.pop(k)
        escaped_fields=list(map(lambda f: '`%s`' % f,fields))
        attrs['__mapping__']=mapping
        attrs['__table__']=tableName
        attrs['__primary_key__']=primaryKey
        attrs['__fields__']=fields
        attrs['__select__']='select `%s`,%s from `%s`' % (primaryKey,', '.join(escaped_fields),tableName)
        attrs['__insert__']='insert into `%s`(%s,`%s`) values(%s)' % (tableName,', '.join(escaped_fields),primaryKey,create_args_string(len(escaped_fields)+1))
        attrs['__update__']='update `%s` set %s where `%s`=?' % (tableName,', '.join(map(lambda f:'`%s`=?' % (mapping.get(f).name or f),fields)),primaryKey)
        attrs['__delete__']='delete from `%s` where `%s`=?' % (tableName,primaryKey)
        return type.__new__(cls,name,bases,attrs)

class Model(dict,metaclass=ModelMetaClass):
    def __init__(self,**kw):
        super(Model,self).__init__(**kw)
    def __getattr__(self,key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(r"'Model' object has no attribute '%s'" % key)
    def __setattr__(self,key,value):
        self[key]=value
    def getValue(self,key):
        return getattr(self,key,None)
    def getValueOrDefault(self,key):
        value=getattr(self,key,None)
        if value is None:
            field=self.__mapping__[key]
            if field.default is not None:
                value=field.default() if callable(field.default) else field.default
                logging.debug('using default value for %s : %s ' % (key,str(value)))
                setattr(self,key,value)
        return value
    @classmethod
    async def findAll(cls,where=None,args=None,**kw):
        ' find objects by where clause.'
        sql = [cls.__select__]
        if where:
            sql.append('where')
            sql.append(where)
        if args is None:
            args=[]
        orderBy = kw.get('orderBy',None)
        if orderBy:
            sql.append('order by')
            sql.append(orderBy)
        limit=kw.get('limit',None)
        if limit is not None:
            sql.append('limit')
            if isinstance(limit,int):
                sql.append('?')
                args.append(limit)
            elif isinstance(limit,tuple) and len(limit)==2:
                sql.append('?,?')
                args.extend(limit)
            else:
                raise ValueError('Invalid limit value: %s ' % str(limit))
        rs = await select(' '.join(sql),args)
        return [cls(**r) for r in rs]
    
    @classmethod
    async def findNumber(cls,selectField,where=None,args=None):
        ' find number by select and where.'
        sql=['select %s _num_ from `%s`' % (selectField,cls.__table__)]
        if where:
            sql.append('where')
            sql.append(where)
        rs=await select(' '.join(sql),args,1)
        if len(rs)==0:
            return None
        return rs[0]['_num_']
    
    @classmethod
    async def find(cls,pk):
        ' find object by primarykey'
        rs= await select('%s where `%s`=?' % (cls.__select__,cls.__primary_key__),[pk],1)
        if len(rs)==0:
           return None
        return cls(**rs[0])
    
    async def save(self):
        args=list(map(self.getValueOrDefault,self.__fields__))
        args.append(self.getValueOrDefault(self.__primary_key__))
        rows= await execute(self.__insert__,args)
        if rows !=1:
            logging.warn('failed to insert record : affected rows: %s ' % rows)
    
    async def update(self):
       args=list(map(self.getValue,self.__fields__))
       args=append(self.getValue(self.__primary_key__))
       rows=await execute(self.__update__,args)
       if rows!=1:
           logging.warn('failed to update by primary key: affected rows: %s' % rows)
    
    async def remove(self):
        args=[self.getValue(self.__primary_key__)]
        rows=await execute(self.__delete__,args)
        if rows!=1:
            logging.warn('failed to remove by primary key: affected rows: %s' % rows)



